826-34-6Relevant articles and documents
Nickel(0)-Catalyzed Reactions of Bicyclobutanes. Geminal Two-Bond Cleavage Reaction and the Stereospecific Olefin Trapping of the Carbenoid Intermediate.
Takaya, H.,Suzuki, T.,Kumagai, Y.,Hosoya, M.,Kawauchi, H.,Noyori, R.
, p. 2854 - 2861 (1981)
Zerovalent nickel complexes such as bis(acrylonitrile)nickel(0) or bis(1,5-cyclooctadiene)nickel(0) catalyze the reaction of bicyclobutanes and electron-deficient olefins such as methyl acrylate and acrylonitrile to give the corresponding allylcyclopropane derivatives in excellent yields.The reaction of 3-deuterio-1,2,2-trimethylbicyclobutane indicates that the two-bond cleavage occurs at the central ? bond and one of the four peripheral bonds of bicyclobutanes to generate an allylcarbene-nickel complex as the reactive intermediate.The reactionof bicyclobutane with (Z)-β-deuterioacrylate or a pair of E and Z 1,2-disubstituted olefins proceeded with a high degree of stereospecificity.The mechanism of cycloaddition is discussed.
Fate of diradicals in the caldera: Stereochemistry of thermal stereomutation and ring enlargement in cis- and trans-1-cyano-2(E)- propenylcyclopropanes
Doering, William Von E.,Barsa, Edward Albert
, p. 12353 - 12362 (2007/10/03)
This study of thermally induced stereomutation and ring enlargement in both (-)-trans-1-cyano-2(E)-propenylcyclopropane [(-)-trans-1] and (+)-cis-1-cyano-2(E)-propenylcyclopropane [(+)-cis-1] to cyclopentenes definitively contraindicates the usefulness of Woodward-Hoffmann rules of orbital symmetry as a theoretical basis for predicting the stereochemistry of the products. From both diastereomers, the same (+)-trans-4-cyano-3- methylcyclopentene [(+)-trans-2] is the major product among the four diastereomeric products, "allowed" and formally the result of a single internal rotation of the cyano-bearing carbon atom from (-)-trans-1, "forbidden" and the result of zero internal rotations from (+)-cis-1. Stereomutation and ring enlargement are discussed in detail in terms of rotational propensity, thermodynamic preference, and the possible role of diradicals in transit and diradicals as intermediates in a caldera.
Cyclopropane formation by nickel-catalysed electroreductive coupling of activated olefins and unactivated gem-dibromo compounds
Sengmany, Stéphane,Léonel, Eric,Paugam, Jean Paul,Nédélec, Jean-Yves
, p. 271 - 277 (2007/10/03)
Cyclopropyl derivatives have been prepared with good yields by transition-metal catalysed electroreductive coupling of activated olefins and unactivated gem-dibromo compounds. This electrolysis is characterized by the use of a Fe/Ni catalyst system, acetonitrile as the solvent and a catalytic amount of triphenylphosphine as ligand. This procedure is a good alternative to the classical preparations of cyclopropyl derivatives from activated olefins (Simmons-Smith reaction, 1,3-dipolar addition of diazomethane, 1,4-addition of phosphorus and sulfur ylides).
Enantioselective synthetic approaches to cyclopropane and cyclobutane β-amino acids: Synthesis and structural study of a conformationally constrained β-dipeptide
Martin-Vila, Marta,Muray, Elena,Aguado, Gemma P.,Alvarez-Larena, Angel,Branchadell, Vicenc,Minguillon, Cristina,Giralt, Ernest,Ortuo, Rosa M.
, p. 3569 - 3584 (2007/10/03)
Synthetic approaches to carbocyclic compounds, namely cyclopropane and cyclobutane β-amino acids, are presented. One of them is based on enzymatic desymmetrization of meso diesters, leading to the enantioselective production of cis-hemiesters, which afforded β-amino acids through Curtius rearrangements. The enantiomeric excess for the cyclobutane derivatives was 91% whereas the cyclopropanes were obtained in 63% ee. According to another strategy, an enantiomerically pure cyclopropane trans-β-amino acid, bearing a quaternary center, has been synthesized from a homochiral precursor easily available from D-glyceraldehyde. The preparation and structural investigation of the first synthesized cyclobutane containing dipeptide is also described. A hairpin-like conformation of this molecule in the solid state has been demonstrated by X-ray structural analysis, showing crystal packing induced by the presence of the rigid cyclobutane moiety and the formation of intermolecular hydrogen bonds. NMR experiments confirmed that these molecules also tend to produce aggregates in solution. On the contrary, theoretical calculations suggest that intramolecular interactions are important in the gas phase, as expected. Copyright (C) 2000 Elsevier Science Ltd.
Coordination Catalysis in Organic Electrosynthesis. Stoichiometry and Products of Reduction of Dibromomethane by Ni(0) Complexes with π-Acceptor Ligands
Budnikova,Petrukhina,Kargin
, p. 257 - 259 (2007/10/03)
Reaction of Ni(0) complexes with dibromomethane gives different final products depending on the nature of the process in the stage of oxidative addition, which proceeds either through the elimination of two bromide ions to give intermediate carbene, or by the elimination of one bromide ion, depending on the ligand enviroment in the metal complex.
Synthesis of Cyclopropyl Carbocyclic Nucleosides
Csuk, Rene,Scholz, Yvonne von
, p. 10431 - 10442 (2007/10/02)
As representatives of a novel class of carboxylic nucleoside analogues (+/-)-cis-, (-)-cis and (+/-)-trans 9-(2-hydroxymethylcyclopropyl)-adenine (= -methanol) were synthesized from the corresponding dialkyl 1,2-cyclopropane dicarboxylates.
Stereoselective 1,3-debromination reactions
Liu, Yingchun,Sorensen, Ted S.,Sun, Fang
, p. 258 - 262 (2007/10/02)
The metallate, PPN(1+)Cr(CO)4NO(1-), was used for the 1,3-debrominative reductive cyclization of the (+/-) and meso isomers of dimethyl 2,4-dibromoglutarate and dimethyl 2,4-dibromo-2,4-dimethylglutarate.In both (+/-) isomers, the reaction is stereospecific in giving the trans cyclopropane product.In the meso case, the reaction is unselective in the first case, but distinctly favors the cis cyclopropane isomer in the second set of compounds.This (+/-) and meso pair thus represent the first example of near stereospecifity in the debromination of both 1,3-dibromo diasteromers.Using an enantiomerically enriched dimethyl 2,4-dibromo glutarate, and determining the absolute stereochemistry of the cyclopropane product, it was found that a strict double inversion () mechanism is involved in the (+/-) debromination reaction and presumably also in the near-stereospecific meso case reported above.
Synthesis of Dimethyl 1,2-Cycloalkanedicarboxylates by Electrochemical Cyclization of Dimethyl α,α-Dibromoalkanedioates Using a Copper Anode
Tokuda, Masao,Hayashi, Atsushi,Suginome, Hiroshi
, p. 2590 - 2592 (2007/10/02)
The electrochemical cyclization of dimethyl α,α'-dibromoalkanedioates by making use of a platinum cathode and a copper anode in the presence of sodium iodide gave three- to six-membered dimethyl 1,2-cycloalkanedicarboxylates in good yields.
184. Stereoselective Hydrolysis of Substituted Cyclopropanedicarboxylates with Pig Liver Esterase
Walser, Paula,Renold, Peter,N'Goka, Victor,Hosseinzadeh, Fatemeh,Tamm, Christoph
, p. 1941 - 1952 (2007/10/02)
The hydrolysis of the meso-cyclopropane-1,2-dicarboxylates 1a-3a, 4, 5a, 6a, and 9, containing various substituents at C(3), and of the rac-3-phenylcyclopropane-1,2-dicarboxylates 7a, 8a, and 10 with pig liver esterase (PLE) is described.The stereoselectivity and absolute configurations of the products were determined.An interpretation of results was attempted on the basis of a recent active-site model for PLE.
Facile Synthesis of Racemic 3-Acetoxy-2,6-dimethyl-1,5-heptadiene, the Sex Pheromone of the Comstock Mealybug
Skatteboel, Lars,Stenstroem, Yngve
, p. 93 - 96 (2007/10/02)
A three step synthesis of 3-acetoxy-2,6-dimethyl-1,5-heptadiene is described.Starting from methyl chloroacetate and methyl acrylate, trans- and cis-dimethyl 1,2-cyclopropanedicarboxylate have been prepared.The isomers were treated with methyllithium or methylmagnesium iodide to give the corresponding diols in high yields.Heating the trans diol in a mixture of acetic acid and acetic anhydride at 80 deg C gave the title compound in an overall yield of 50percent based on methyl chloroacetate.The corresponding cis diol gave, under the same conditions, 2,2,4,4-tetramethyl-3-oxabicyclohexane as the only product.
